Non-resonant magnetic resonance coil and magnetic resonance imaging system using the same

ABSTRACT

A magnetic resonance coil and a magnetic resonance imaging system using the same are provided. The magnetic resonance coil may include an antenna and a signal processor. The antenna may be configured to receive a radio frequency (RF) signal emitted from an object, wherein the antenna does not resonate with the RF signal. The signal processor may be coupled to the antenna configured to process the RF signal to generate a processed signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of Chinese Patent Application No.201710581577.X, filed on Jul. 17, 2017, Chinese Patent Application No.201710582369.1, filed on Jul. 17, 2017, and Chinese Patent ApplicationNo. 201710582372.3, filed on Jul. 17, 2017, the contents of which arehereby incorporated by reference.

TECHNICAL FIELD

The present disclosure generally relates to a radio frequency (RF) coil,and more particularly, to an RF coil implemented in a magnetic resonanceimaging system for receiving an RF signal emitted from an object.

BACKGROUND

Magnetic resonance imaging (MRI) is an imaging technique used inradiology to form images of the anatomy and the physiological processesof an object (e.g., a patient, or a section thereof). MRI scanners usestrong magnetic fields, radio waves, and field gradients to generateimages of the inner structure of the object based on the science ofnuclear magnetic resonance (NMR). More particularly, certain atomicnuclei (e.g., hydrogen-1, carbon-13, oxygen-17, etc.) absorb and emit RFenergy when placed in an external magnetic field. The emitted RF energyexists as RF signals and is received by the MRI scanners.

Hydrogen atoms are often used to generate a detectable RF signal that isreceived by an antenna of a coil in close proximity to the object beingexamined. Conventionally, the antenna includes capacitance, conductance,and/or resistance that provide the antenna a specific resonantfrequency. When the frequency of the RF signal emitted from the objectmatches the resonant frequency of the antenna, the antenna resonates andreceives the RF signal. Hence, the antenna has to be designed carefullyso that the resonant frequency exactly matches the frequency of the RFsignal emitted from the object. However, the antenna is usually deformed(bent) in use and the resonant frequency changes. When the resonantfrequency no longer matches the frequency of the RF signal emitted fromthe object, the coil does not work as well as before and the RF signalis received at a lower quality (e.g., with a lower signal-to-noise ratio(SNR)). Therefore, it is desired to develop a coil that is able toreceive the RF signal even when it is deformed.

SUMMARY

In an aspect of the present disclosure, a magnetic resonance coil isprovided. The magnetic resonance coil may include an antenna configuredto receive a radio frequency (RF) signal emitted from an object, whereinthe antenna does not resonate with the RF signal. The magnetic resonancecoil may further include a signal processor coupled to the antennaconfigured to process the RF signal to generate a processed signal.

In some embodiments, the antenna is a non-resonant antenna.

In some embodiments, the antenna may be made of one or more deformableconductive materials.

In some embodiments, the antenna may be a birdcage structure configuredto receive the RF signal from an entire body of the object.

In some embodiments, the antenna may be a loop structure configured toreceive the RF signal from a portion of the object.

In some embodiments, the signal processor may include an amplifiercoupled to the antenna and configured to amplify the RF signal.

In some embodiments, the amplifier is a differential amplifier.

In some embodiments, the magnetic resonance coil may further include amatching circuit coupled between the antenna and the amplifier andconfigured to match an impedance of the antenna and an impedance of theamplifier.

In some embodiments, the matching circuits is a broadband matchingcircuit that matches the impedance of the antenna and the impedance ofthe amplifier over a frequency range of the broadband signals.

In some embodiments, the magnetic resonance coil may further include anadjusting circuit coupled to the amplifier and configured to adjust themagnitude of the imaginary part of impedance of the amplifier.

In some embodiments, the adjusting circuit may include at least one of avariable capacitor or a variable conductor.

In some embodiments, the signal processor may further include a filtercoupled to the amplifier.

In some embodiments, the signal processor may further include aheterodyne receiver or a homodyne receiver coupled to the amplifier.

In some embodiments, the signal processor is a direct samplingstructure, and the signal processor may include an analog-to-digitalconverter configured to convert the RF signal to a digital signal.

In some embodiments, the antenna may be configured without capacitiveelements on conductive materials.

In some embodiments, the antenna may be configured with no impedancematching circuit.

In some embodiments, the amplifier may be configured with an inputimpedance greater than 500 Ohms.

In some embodiments, the antenna may be configured with no couplingunit, nor decoupling unit.

In some embodiments, the magnetic resonance coil may be implemented in amulti-nuclear magnetic resonance system relating to a plurality ofatomic nuclei. The plurality of atomic nuclei may include phosphorusatom or sodium atom.

In another aspect of the present disclosure, a magnetic resonanceimaging (MRI) system is provided. The MRI system may include a mainelectromagnet configured to generate a uniform magnetic field on anobject, and a gradient electromagnet configured to generate a gradientmagnetic field on the object. The MRI system may further include atransmitting coil configured to transmit a first radio frequency (RF)signal to the object, and a receiving coil configured to receive andprocess a second RF signal emitted from the object in response to thefirst RF signal. The receiving coil may include an antenna configured toreceive a radio frequency (RF) signal emitted from an object, whereinthe antenna does not resonate with the RF signal. The receiving coil mayfurther include a signal processor coupled to the antenna configured toprocess the RF signal to generate a processed signal. The MRI system mayinclude a processor configured to generate an image of the object basedon the processed signal. The MRI system may include a display configuredto display the generated image of the object.

Additional features will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the artupon examination of the following and the accompanying drawings or maybe learned by production or operation of the examples. The features ofthe present disclosure may be realized and attained by practice or useof various aspects of the methodologies, instrumentalities andcombinations set forth in the detailed examples discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplaryembodiments. These exemplary embodiments are described in detail withreference to the drawings. These embodiments are non-limiting examples,in which like reference numerals represent similar structures throughoutthe several views of the drawings, and wherein:

FIG. 1 is a schematic block diagram of an exemplary magnetic resonanceimaging (MRI) system according to some embodiments of the presentdisclosure;

FIG. 2 is a flowchart illustrating an exemplary process for processingan RF signal according to some embodiments of the present disclosure;

FIG. 3 is a flowchart illustrating an exemplary process for processingan RF signal according to some embodiments of the present disclosure;

FIG. 4 is a schematic diagram illustrating an exemplary magneticresonance RF coil according to some embodiments of the presentdisclosure;

FIG. 5 is a schematic diagram illustrating an exemplary analog signalprocessor according to some embodiments of the present disclosure;

FIG. 6 is a schematic diagram illustrating an exemplary analog signalprocessor according to some embodiments of the present disclosure;

FIG. 7 is a schematic diagram illustrating an exemplary analog signalprocessor according to some embodiments of the present disclosure;

FIG. 8 is a schematic diagram illustrating an exemplary magneticresonance RF coil according to some embodiments of the presentdisclosure;

FIG. 9 is a schematic diagram illustrating an exemplary magneticresonance RF coil according to some embodiments of the presentdisclosure;

FIG. 10 is a schematic diagram illustrating an exemplary magneticresonance RF coil according to some embodiments of the presentdisclosure;

FIG. 11 is a schematic diagram illustrating an exemplary amplifyingcircuit according to some embodiments of the present disclosure; and

FIG. 12 is a schematic diagram illustrating an exemplary double terminalnetwork according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant disclosure. However, it should be apparent to those skilledin the art that the present disclosure may be practiced without suchdetails. In other instances, well-known methods, procedures, systems,components, and/or circuitry have been described at a relativelyhigh-level, without detail, in order to avoid unnecessarily obscuringaspects of the present disclosure. Various modifications to thedisclosed embodiments will be readily apparent to those skilled in theart, and the general principles defined herein may be applied to otherembodiments and applications without departing from the spirits andscope of the present disclosure. Thus, the present disclosure is notlimited to the embodiments shown, but to be accorded the widest scopeconsistent with the claims.

It will be understood that the term “system,” “unit,” “module,” and/or“block” used herein are one method to distinguish different components,elements, parts, section or assembly of different level in ascendingorder. However, the terms may be displaced by another expression if theymay achieve the same purpose.

It will be understood that when a unit, module or block is referred toas being “on,” “connected to” or “coupled to” another unit, module, orblock, it may be directly on, connected or coupled to the other unit,module, or block, or intervening unit, module, or block may be present,unless the context clearly indicates otherwise. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

The terminology used herein is for the purposes of describing particularexamples and embodiments only, and is not intended to be limiting. Asused herein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “include,”and/or “comprise,” when used in this disclosure, specify the presence ofintegers, devices, behaviors, stated features, steps, elements,operations, and/or components, but do not exclude the presence oraddition of one or more other integers, devices, behaviors, features,steps, elements, operations, components, and/or groups thereof.

The present disclosure provides a magnetic resonance coil implemented inan MRI system. The present magnetic resonance coil may receive an RFsignal generated by an object being examined even when it is deformed.The magnetic resonance coil may include an antenna that does notresonate with the RF signal and a signal processor coupled to theantenna configured to process the RF signal. In some embodiments,different atoms may emit RF signals at different frequencies. As thenon-resonant RF antenna may receive RF signals at a wide range offrequencies, it may be used to image atoms, such as a phosphorus atom, asodium atom, etc. besides the atoms that are commonly imaged in an MRIsystem (e.g., hydrogen atoms, carbon atoms, oxygen atoms). The antennamay be a birdcage structure configured to receive the RF signal from anentire body of the object or may be a loop structure configured toreceive the RF signal from a portion of the object. The signal processormay be an analog signal processor or a digital signal processor. Thesignal processor may include an amplifier configured to amplify thereceived RF signal. The magnetic resonance coil may include an adjustingcircuit configured to adjust the magnitude of the imaginary part ofimpedance of the amplifier. The input impedance of the amplifier may begreater than 500 Ohms.

FIG. 1 is a schematic block diagram of an exemplary magnetic resonanceimaging (MRI) system 100 according to some embodiments of the presentdisclosure. As shown in FIG. 1, the MRI system 100 may include a MRIscanner 130, a computing device 140, a processing engine 122, and astorage device 125. It should be noted that the imaging system describedbelow is merely provided for illustration purposes, and not intended tolimit the scope of the present disclosure. The MRI system 100 may findits applications in various fields, such as healthcare industries (e.g.,medical applications), security applications, industrial applications,etc. For example, the MRI system 100 may be used for analyzingcomposition of a specimen, nuclear magnetic resonance logging, or thelike, or a combination thereof.

The MRI scanner 130 may include a main magnet 101, a gradient magnet102, a volume coil 103, a local coil 104, a scanning bed 106, an pulsecontroller 111, a gradient signal generator 112, a first gradientamplifier 113, a second gradient amplifier 114, a third gradientamplifier 115, an RF pulse generator 116, a switch 117, and an RF signalreceiver 118. A detecting region 105 may be formed in the MRI scanner130. The detecting region 105 may be a place where the object is scannedby the MRI scanner 130.

The MRI scanner 130 may be configured to scan an imaging object 150. TheMRI scanner 130 may obtain information related to the imaging object 150by scanning the imaging object 150. More particularly, certain atomicnuclei (e.g., hydrogen-1, carbon-13, oxygen-17, etc.) may absorb andemit RF energy when being placed in the main magnetic 101 and thegradient magnet 102. The emitted RF energy exists as RF signals and isreceived by the MRI scanner 130. The MRI scanner 130 may reconstruct adistribution of the atomic nuclei inside the imaging object based on theRF signals as an MRI image.

The main magnet 101 may be placed in a gantry 145 of the MRI scanner.The main magnet 101 may be configured to generate a uniform mainmagnetic field. The strength of the main magnetic field may be 0.2Tesla, 0.5 Tesla, 1.0 Tesla, 1.5 Tesla, 3.0 Tesla, etc. In someembodiments, the main magnet 101 may be a superconducting coil.Alternatively, the main magnet 101 may be a permanent magnet.

The scanning bed 106 may support the imaging object 150 during a scan.The object may be biological or non-biological. Merely by way ofexample, the object may include a patient, an organ, a specimen, aman-made object, a mold, etc. During a scan, the imaging object 150 maybe supported and delivered to the detecting region 105 of the gantry 145by the scanning bed 106. The detecting region 105 may be a region thatthe magnetic field distribution of the main magnetic field is relativelyuniform, and to which, the RF signal is transmitted.

Merely by way of example, a spatial coordinate system (i.e., acoordinate system of the MRI scanner) may be described relative to thegantry 145 of the MRI scanner 130. For example, a Z axis may be thedirection along the axis of the gantry, an X axis and a Y axis may bethe directions perpendicular to the Z axis. The long-axis direction ofthe imaging object may coincide with the direction of the Z axis and thescanning bed 106 may move in the direction of the Z axis.

The pulse controller 111 may be configured to control the generation ofRF signals. For example, the pulse controller 111 may control the RFpulse generator 116 and the gradient signal generator 112. In someembodiments, the pulse controller 111 may control the RF pulse generator116 to generate an RF pulse. The RF pulse may be amplified by anamplifier. In some embodiments, the pulse controller 111 may control thegradient signal generator 112 to generate gradient signals.

The pulse controller 111 may receive information from or sendinformation to the MRI scanner, the processing engine 122, and/or adisplay 123. According to some embodiments of the present disclosure,the pulse controller 111 may receive a command from a user via thedisplay 123 and control components of the MRI scanner (e.g., the RFpulse generator 116) accordingly to start a scan.

The RF pulse generator 116 may generate an RF pulse. In someembodiments, the RF pulse generator 116 may generate the RF pulse basedon an instruction from the pulse controller 111. The RF pulse may beamplified by an amplifier. The switch 117 may be configured to controlthe emission of the amplified RF pulse. For example, the amplified RFpulse may be emitted by the volume coil 103 and/or the local coil 104when the switch 117 is on. The emitted RF pulse may excite the atomicnuclei in the imaging object 150. The imaging object 150 may generate acorresponding RF signal when the RF excitation is removed. The volumecoil 103 and/or the local coil 104 may transmit RF signals to or receiveRF signals from the imaging object 150. For example, the volume coil 103and/or the local coil 104 may transmit the amplified RF pulse to theimaging object 150. For another example, the volume coil 103 and/or thelocal coil 104 may receive the RF signal emitted from the imaging object150. In some embodiments, the volume coil 103 and/or the local coil 104may include a plurality of RF receiving channels. The plurality of RFreceiving channels may transmit RF signals received from the imagingobject 150 to the RF signal receiver 118. In some embodiments, thevolume coil 103 may be configured to transmit RF signals to or receiveRF signals from the entire body of the imaging object 150 while thelocal coil 104 may be configured to transmit RF signals to or receive RFsignals from a portion of the imaging object 150.

The volume coil 103 and/or the local coil 104 may bemagnetically-insulated. In some embodiments, the volume coil 103 and thelocal coil 104 are non-resonant coils which do not include anycapacitance. The volume coil 103 and/or the local coil 104 may be madeof one or more deformable materials. For example, the volume coil 103and/or the local coil 104 may be made of shape-memory alloy. Theshape-memory alloy may recover to its original shape under a recoveringcondition (e.g., a high temperature, a large strain). The shape-memoryalloy may include silver, cadmium, gold, nickel, titanium, hafnium,copper, zinc, or the like, or any combination thereof. For anotherexample, the volume coil 103 and/or the local coil 104 may be made ofdeformable conductive materials. The deformable conductive materials mayinclude metallic materials such as solid metals, alloys, liquid metals,etc. The liquid metals may include mercury, aluminum, cesium, gallium,rubidium, or the like, or any combination thereof.

In some embodiments, the volume coil 103 may be a large coil (e.g., abirdcage coil) that can accommodate the entire body of the imagingobject 150. The local coil 104 may be a small coil (e.g., a loop coil, asolenoid coil, a saddle coil, a flexible coil, etc.) that covers aportion of the imaging object 150.

The RF signal receiver 118 may be configured to receive RF signals. TheRF signal receiver 118 may receive RF signals from the volume coil 103and/or the local coil 104.

The gradient signal generator 112 may generate gradient signals. In someembodiments, the gradient signal generator 112 may generate gradientsignals based on an instruction from the pulse controller 111. Thegradient signals may include three orthogonal signals. In someembodiments, the three orthogonal signals may be a first gradient signalalong the X direction, a second gradient signal along the Y direction,and a third gradient signal along the Z direction. The gradient signalsmay help to locate the atomic nuclei.

The first gradient amplifier 113, the second gradient amplifier 114, andthe third gradient amplifier 115 may be configured to amplify thegradient signals generated by the gradient signal generator 112. Inparticular, the first gradient amplifier 113 may amplify the firstgradient signal, the second gradient amplifier 114 may amplify thesecond gradient signal, and the third gradient amplifier 115 may amplifythe third gradient signal, respectively.

The gradient magnet 102 (also called gradient coil 102) may beconfigured to spatially encode RF signals (e.g., an RF pulse generatedby the RF pulse generator 116). The gradient magnet 102 may generate amagnetic field with a strength less than that of the main magneticfield. For example, the gradient magnet 102 may generate a gradientmagnet field in the detecting region 105.

In some embodiments, the MRI scanner 130 may include both a volume coil103 and a local coil 104. For example, the volume coil 103 may beconfigured to emit RF signals, and the local coil may be configured toreceive RF signals, or vice versa. The volume coil 103 and the localcoil 104 may each include an amplifier with a high input impedancevalue, respectively. The amplifiers with high input impedance maydecouple the volume coil and the local coil without additionaldecoupling methods.

The computing device 140 may include a reconstruction module 121, thedisplay 123, an input/output (I/O) 124, and a communication port 126.

The reconstruction module 121 may be configured to reconstruct an MRIimage. The reconstruction module 121 may reconstruct an MRI image basedon RF signals received by the RF signal receiver 118.

The display 123 may be configured to display images. The display 123 mayinclude a liquid crystal display (LCD), a light emitting diode(LED)-based display, or any other flat panel display, or may use acathode ray tube (CRT), a touch screen, or the like. A touch screen mayinclude, e.g., a resistor touch screen, a capacity touch screen, aplasma touch screen, a vector pressure sensing touch screen, an infraredtouch screen, or the like, or a combination thereof.

The I/O 124 may input and/or output signals, data, information, etc. Theinput and/or output information may include programs, software,algorithms, data, text, number, images, voice, or the like, or anycombination thereof. For example, a user or an operator may input someinitial parameters or conditions to initiate a scan. As another example,some information may be imported from an external resource, such as afloppy disk, a hard disk, a wireless terminal, or the like, or anycombination thereof. In some embodiments, the I/O 124 may enable a userinteraction with the processing engine 122. In some embodiments, the I/O124 may include an input device and an output device. Examples of theinput device may include a keyboard, a mouse, a touch screen, a controlbox, a microphone, or the like, or a combination thereof. Examples ofthe output device may include a display device, a loudspeaker, aprinter, a projector, or the like, or a combination thereof.

The communication port 126 may be connected to a network (not shown) tofacilitate data communications. The communication port 126 may establishconnections between an external device, an image acquisition device, adatabase, an external storage, and an image processing workstation, etc.The connection may be a wired connection, a wireless connection, anyother communication connection that can enable data transmission and/orreception, and/or any combination of these connections. The wiredconnection may include, for example, an electrical cable, an opticalcable, a telephone wire, or the like, or any combination thereof. Thewireless connection may include, for example, a Bluetooth™ connection, aWi-Fi™ connection, a WiMax™ connection, a WLAN connection, a ZigBeeconnection, a mobile network connection (e.g., 3G, 4G, 5G, etc.), or thelike, or a combination thereof. In some embodiments, the communicationport 126 may include a standardized communication port, such as RS232,RS485, etc. In some embodiments, the communication port 126 may be aspecially designed communication port. For example, the communicationport 126 may be designed in accordance with the digital imaging andcommunications in medicine (DICOM) protocol.

The processing engine 122 may process different kinds of information.For example, the processing engine 122 may process RF signals receivedfrom the RF signal receiver 118 to the reconstruction module 121 togenerate one or more images based on these signals and sent the imagesto the display 123. In some embodiments, the processing engine 122 mayprocess data input by a user or an operator via the display 123 and/orthe I/O 124, transform the data into specific commands, and supply thecommands to the pulse controller 111. The processing engine 122 mayinclude one or more processors.

The storage device 125 may store data relating to the MRI system 100.The data may be data files related to processing and/or communication,program command to be executed by the processor engine 112, a numericalvalue, an image, information of an object, an instruction and/or asignal to operate the MRI system 100, voice, a model relating to apatient, an algorithm relating to an image processing technique, or thelike, or a combination thereof. Exemplary numerical values may include athreshold, a MR value, a value relating to a coil, or the like, or acombination thereof. Exemplary images may include a raw image or aprocessed image (e.g., an image after pretreatment). Exemplary modelsrelating to a patient may include the background information of thepatient, such as, ethnicity, citizenship, religion, gender, age,matrimony state, height, weight, medical history (e.g., history relatingto different organs, or tissues), job, personal habits, or the like, ora combination thereof.

The storage device 125 may include a random access memory (RAM), aread-only memory (ROM), or the like, or a combination thereof. Therandom access memory (RAM) may include a dekatron, a dynamic randomaccess memory (DRAM), a static random access memory (SRAM), a thyristorrandom access memory (T-RAM), a zero capacitor random access memory(Z-RAM), or the like, or a combination thereof. The read only memory(ROM) may include a bubble memory, a magnetic button line memory, amemory thin film, a magnetic plate line memory, a core memory, amagnetic drum memory, a CD-ROM drive, a hard disk, a flash memory, orthe like, or a combination thereof. The storage device 125 may be aremovable storage device such as a chip disk that may read data fromand/or write data to the reconstruction module 121 in a certain manner.The storage device 125 may also include other similar means forproviding computer programs or other instructions to operate themodules/units in the MRI system 100. The storage device 125 may beoperationally connected to one or more virtual storage resources (e.g.,a cloud storage, a virtual private network, other virtual storageresources, etc.) for transmitting or storing the data into the one ormore virtual storage resources.

In some embodiment, the pulse controller 111, the reconstruction module121, the processing engine 122, the display 123, the I/O 124, thestorage device 125, and the communication port 126 may transmit data toeach other via a communication bus 127 to control an imaging process ofthe MRI scanner 130.

This description is intended to be illustrative, and not to limit thescope of the present disclosure. Many alternatives, modifications, andvariations will be apparent to those skilled in the art. The features,structures, methods, and other characteristics of the exemplaryembodiments described herein may be combined in various ways to obtainadditional and/or alternative exemplary embodiments. For example, thestorage device 125 may be a database including cloud computingplatforms, such as a public cloud, a private cloud, a community andhybrid clouds, etc. As another example, the pulse controller 111, theprocessing engine 122, and/or the display 123 may be integrated into anMRI console (not shown). Users may set parameters in MRI scanning,control the imaging procedure, view the images produced through the MRIconsole. However, those variations and modifications do not depart thescope of the present disclosure.

FIG. 2 is a flowchart illustrating an exemplary process for processingan RF signal according to some embodiments of the present disclosure. Insome embodiments, a process 300 may be implemented in the MRI system 100as illustrated in FIG. 1.

In 202, an RF signal emitted from an object may be received by an RFreceiving coil. The RF receiving coil may be a non-resonant coil. Theobject may be biological or non-biological. Merely by way of example,the object may include a patient, an organ, a specimen, a man-madeobject, a mold, etc. The RF signal may be an analog signal or a digitalsignal. As mentioned in FIG. 1, the object may be placed in a magneticfield and a volume coil 103 and/or a local coil 104 may transmit an RFsignal to the object. The transmitted RF signal may excite atomic nucleiin the imaging object 150. The imaging object 150 may generate acorresponding RF signal when the RF excitation is removed. The objectmay emit the RF signal based on relaxation properties of atomic nucleitherein. The atomic nuclei may include hydrogen-1, carbon-13, oxygen-17,sodium 23, phosphorus-31, or the like, or any combination thereof.

In 204, the received RF signal may be processed to generate a processedsignal. In some embodiments, the processing engine 122 may first processthe RF signal and then convert the processed RF signal to a digitalsignal. For example, the processing engine 122 may amplify the RFsignal, filter the amplified RF signal to generate a processed RFsignal, and then convert the processed RF signal to a digital signal. Insome embodiments, the processing engine 122 may convert the RF signal toa digital RF signal before processing the signal. For example, ananalog-to-digital converter may be configured to convert the RF signalto a digital signal. Digital signal processing may include procedures ofsignal amplification, frequency conversion, filtering, notch, or thelike, or any combination thereof.

FIG. 3 is a flowchart illustrating an exemplary process for processingan RF signal according to some embodiments of the present disclosure. Insome embodiments, the process 300 may be implemented in the MRI system100 as illustrated in FIG. 1.

In 302, an RF signal emitted from an object may be received by a RFreceiving coil (e.g., volume coil 103, local coil 104, etc.). The RFreceiving coil may be a non-resonant coil. The object may be biologicalor non-biological. Merely by way of example, the object may include apatient, an organ, a specimen, a man-made object, a mold, etc. The RFsignal may be an analog signal or a digital signal. As mentioned in FIG.1, the object may be placed in a magnetic field and a volume coil 103and/or a local coil 104 may transmit an RF signal to the object. Thetransmitted RF signal may excite atomic nuclei in the imaging object150. The imaging object 150 may generate a corresponding RF signal whenthe RF excitation is removed. The object may emit the RF signal based onrelaxation properties of atomic nuclei therein. The atomic nuclei mayinclude hydrogen-1, carbon-13, oxygen-17, sodium 23, phosphorus-31, orthe like, or any combination thereof.

In some embodiments, the RF signal may be an analog signal. The RFsignal may be converted to a digital signal before further processing(see, e.g., step 304 to step 308). In some embodiments, the RF signalmay be processed before converted to a digital signal (see, e.g., step310 to step 312).

In 304, the RF signal may be amplified. The processing engine 122 maycontrol an amplifier to amplify the RF signal. The amplifier may becoupled to the RF receiving coil. The amplifier may be a low noiseamplifier. The low noise amplifier may be a component of an analogsignal processor (e.g., an analog signal processor 403). In someembodiments, a matching circuit (e.g., a matching circuit 1003) may beconfigured to match an impedance of the RF receiver with an impedance ofthe amplifier.

In 306, the amplified RF signal may be filtered to generate a filteredsignal. The processing engine 122 may control a filter to filter theamplified RF signal. In some embodiments, the filter may be coupled toan amplifier directly. For example, a low-pass filter may be directlyconnected to the amplifier and filter the amplified RF signal. In someembodiments, the filter may be coupled to a down converter coupled tothe amplifier. For example, the filter may be a channel selection filter(or a bandpass filter) coupled to a down converter. In some embodiments,the filer may be a portion of an analog signal processor.

In 308, the filtered signal may be converted to a digital signal. Theprocessing engine 122 may control an analog-to-digital converter (e.g.,an analog-to-signal converter 903) to convert the filtered signal to adigital signal. In some embodiments, the analog-to-digital converter maybe coupled to an analog signal processor.

In 310, the RF signal may be converted to a digital signal. The RFsignal may be an analog signal. The processing engine 122 may control ananalog-to-digital converter to convert the RF signal to a digitalsignal. The analog-to-digital converter may be coupled to an RFreceiving coil directly.

In 312, the digital signal may be processed. The processing engine 112may control a digital signal processor to process the digital signal.The digital processor may be coupled to the analog-to-digital converter.The signal processing may include procedures of signal amplification,frequency conversion, filtering, notch, or the like, or any combinationthereof.

It should be noted that the flowchart described above is provided forthe purposes of illustration, not intended to limit the scope of thepresent disclosure. For persons having ordinary skills in the art,multiple variations and modifications may be reduced to practice in thelight of the present disclosure. However, those variations andmodifications do not depart from the scope of the present disclosure.For example, other analog or digital signal processing methods may beadded or may replace the current operations in the process 300.

FIG. 4 is a schematic diagram illustrating an exemplary magneticresonance RF coil according to some embodiments of the presentdisclosure. As shown, the magnetic resonance RF coil 400 may include anRF antenna 401, a matching circuit 402, an analog signal processor 403,an analog-to-digital converter 404, a controlling circuit 405, and anenergy supplying circuit 406. It should be noted that the magneticresonance RF coil described herein is merely provided for illustrativepurposes, and not intended to limit the scope of the present disclosure.The magnetic resonance RF coil 400 may find its applications in variousfields, such as healthcare industries (e.g., medical applications),security applications, industrial applications, etc. For example, themagnetic resonance RF coil 400 may be used for internal inspections ofcomponents including, e.g., flaw detection, security scanning, failureanalysis, metrology, assembly analysis, void analysis, wall thicknessanalysis, or the like, or a combination thereof.

The RF antenna 401 may be configured to receive RF signals from anobject (e.g., the imaging object 150). In some embodiments, the RFantenna 401 may be a non-resonant RF antenna. For example, the RFantenna 401 may not include any capacitive components and may notresonant at a fixed frequency. Instead, the RF antenna 401 may beconfigured to resonant and receive signals at a wide range offrequencies (broadband signals). Merely by way of example, an antenna ofa 1.5T MRI system that includes capacitance may resonant at a frequencyfixed at, for example, about 64 MHz. However, the RF antenna 401 mayresonant at a frequency range, e.g., from 57 MHz to 74 MHz. Besides theatoms that are commonly imaged in an MRI system (e.g., hydrogen atoms,carbon atoms, oxygen atoms), the non-resonant RF antenna 401 may be usedto image atoms, such as a phosphorus atom, a sodium atom, etc. The RFantenna 401 may be in a structure of a loop, a solenoid, a saddle, orthe like.

The matching circuit 402 may be electrically connected to the RF antenna401. The matching circuit 402 may be configured to match the impedanceof the RF antenna 401 and that of the analog signal processor 403 toreduce the noise generated in the RF coil 400. In some embodiments, thematching circuit 402 may be a broadband matching circuit which may matchthe impedance of the radio frequency antenna 401 and the analog signalprocessor 403 over a frequency range of the broadband signals.

The analog signal processor 403 may be electrically coupled to thematching circuit 402. The analog signal processor 403 may be configuredto process an analog signal received by the RF antenna 401. For example,the signal process may include procedures of sampling, analog signalamplification, filtering, phase shifting, notch, or the like, or acombination thereof.

The analog-to-digital converter 404 may be configured to convert ananalog signal to a digital signal. The analog-to-digital converter 404may be configured to pre-process the digital signal. For example, theanalog-to-digital converter 404 may compress a digital signal. Foranother example, the analog-to-digital converter 404 may adjust adigital signal. The analog-to-digital converter 404 may be connected toa cable, a fiber optic or a wireless means, via which the digital signalis to be transmitted.

The controlling circuit 405 may be configured to control the analogsignal processor 403 and the analog-to-digital converter 404. Thecontrolling circuit 405 may include a timing circuit with a clocksignal. The clock signal may be configured to control ananalog-to-digital sampling in the analog-to-digital converter 404. Theclock signal may also control the RF coil 401 regarding the acquisitionof RF signals.

The energy supplying circuit 406 may be configured to transmitelectrical power (energy) to the analog signal processor 403 and theanalog-to-digital converter 404. The energy supplying circuit 406 mayinclude a battery pack. The battery pack may supply power to the analogsignal processor 403 and the analog-to-digital converter 404. In someembodiments, the energy supplying circuit 406 may be configured tosupply power to circuits other than analog signal processor 403 and theanalog-to-digital converter 404 of the RF coil 400. For example, theenergy supplying circuit 406 may supply power to the controlling circuit405. In some embodiments, the energy supplying circuit 306 may berechargeable. The energy supplying circuit 406 may be recharged by e.g.,a portable power supply, a direct current (DC) cable or a wirelesscharging device.

In some embodiments, the RF antenna 401 may be a non-resonant antennaand the low noise amplifier may be configured with a high inputimpedance value. Conventionally, a coupling circuit may be configured toresonate at a center frequency, and a decoupling circuit may beconfigured to maintain a receiving coil in a non-working state when atransmitting coil is emitting signals. Due to the high input impedanceof the low noise amplifier, coupling/decoupling circuits between coilsof the RF antenna may be removed, and a signal to noise ratio of RFsignals may be improved. Also due to the high input impedance of the lownoise amplifier, a matching network for matching the input impedance ofan RF antenna and the coupling circuit may be omitted.

In some embodiments, the low noise amplifier with a high input impedancevalue may be configured to receive and output differential signals,avoiding the generation of common-mode signals during signaltransmissions. The common-mode signals may cause unwanted coupling andsignal-to-noise ratio (SNR) loss. The coils may be the volume coils 103,the local coils 104, the gradient coil 102, or the like, or acombination thereof.

FIG. 5 is a schematic diagram illustrating an exemplary analog signalprocessor according to some embodiments of the present disclosure. Asshown in FIG. 5, the analog signal processor 500 may include a low noiseamplifier 501 and a filter 502.

The analog signal processor 500 may be configured to amplify and filteran RF signal received from the RF antenna 401. The low noise amplifier501 may directly sample the RF signal received from the RF antenna 401.The direct sampling architecture may reduce the need of the number ofanalog devices. The performance of the direct sampling architecture maydepend on the processing capacity of the analog-to-digital converter,i.e., a speed and a number of bits of an analog-to-digital converter.The low noise amplifier 501 may be a low noise amplifier with a highgain. The filter 502 may be configured to filter the amplified RFsignal. The filter 502 may be a low-pass filter or a bandpass filter.

FIG. 6 is a schematic diagram illustrating an exemplary analog signalprocessor according to some embodiments of the present disclosure. Asshown in FIG. 6, the analog signal processor 600 may include a low noiseamplifier 601, a down converter 602, a local oscillator 603 and achannel selection filter 604.

The analog signal processor 600 may be a heterodyne receiver. Theheterodyne receiver may convert a received signal (e.g., an amplified RFsignal generated by the low noise amplifier 601) to an intermediatefrequency. The intermediate frequency may satisfy a frequencyrequirement of subsequent components.

The low noise amplifier 601 may be configured to amplify an RF signalreceived by an RF antenna. The amplification may be linear or nonlinear.The local oscillator 603 may be configured to generate a localoscillation signal to be supplied to the low noise amplifier 601.

The down converter 602 may include or may be coupled to a mixer. Themixer may be configured to mix the amplified RF signal and the localoscillation signal. Merely by way of example, the frequency of RF signalmay be expressed as f_(IF) and the frequency of the location oscillationsignal may be expressed as f_(LO). The mixer may generate two signals atf_(LO)+f_(IF) and f_(LO)−f_(IF), respectively. In some embodiments, thedown converter 602 may retain and output the signal at f_(LO)−f_(IF)(which is the intermediate frequency). The channel selection filter 604may be configured to filter the output signal of the down converter 602.In some embodiments, an interference signal may occur at 2f_(1F)−f_(LO)(also called an image frequency). The channel selection filter 604 maybe a bandpass filter to remove the interference signal.

FIG. 7 is a schematic diagram illustrating an exemplary analog signalprocessor according to some embodiments of the present disclosure. Asshown in FIG. 7, the analog signal processor 700 may include a low noiseamplifier 701, a first down converter 702, a first low-pass filter 703,a second down converter 704, a local oscillator 705, a phase-shiftingcircuit 706, and a second low-pass filter 707.

The analog signal processor 700 may be a homodyne receiver. As usedherein, a homodyne receiver may refer to a direct down-convertingreceiver. The carrier frequency of a homodyne receiver (frequency of RFsignal) may be the same as a local frequency (e.g., the frequency of alocal oscillation signal generated by the local oscillator 705).

The homodyne receiver may be related to an orthogonal down-conversion.The orthogonal down-conversion may produce an orthogonal signal I and anorthogonal signal Q. The orthogonal signal I and the orthogonal signal Qmay have same amplitude but different phase. The orthogonaldown-conversion may be realized based on the first down converter 702,the first low-pass filter 703, the second down converter 704, the localoscillator 705, the phase-shifting circuit 706, and the second low-passfilter 707. The low noise amplifier 701 and the local oscillator 705 maybe similar with the low noise amplifier 601 and the local oscillator603, and are not repeated herein. In some embodiments, the localoscillator 705 may generate a local oscillation signal at a frequency ofthe received RF signal. The phase-shifting circuit 706 may shift thelocal oscillation signal by 90 degrees (the amplitude and frequencyremain unchanged) to generate a phase shifted local oscillation signal.

The first down converter 702 may be configured to convert an amplifiedRF signal (e.g., an RF signal amplified by the low noise amplifier 701)to a zero frequency signal based on a phase shifted local oscillationsignal. The method of mixing the phase shifted local oscillation signaland the amplified RF signal is similar to those described in FIG. 6 andis not repeated herein. An output of the first down converter 702 may beinput to the first low-pass filter 703 to generate the orthogonal signalI.

Similarly, the second down converter 704 may be configured to convert anamplified RF signal (e.g., an RF signal amplified by the low noiseamplifier 701) to a zero frequency signal based on a local oscillationsignal. An output of the second down converter 704 may be input to thesecond low-pass filter 707 to generate the orthogonal signal Q.

In some embodiments, the low noise amplifier may be configured with highinput impedance. As used herein, the high input impedance may refer tothe value of input impedance being greater than 500 Ohms, 1000 Ohms, or2000 Ohms. The low noise amplifier with high input impedance may berealized by a field effect transistor (FET), a high electron mobilitytransistor (HEMT), or the like, or a combination thereof.

FIG. 8 is a schematic diagram illustrating an exemplary magneticresonance RF coil according to some embodiments of the presentdisclosure. As shown, the magnetic resonance RF coil 800 may include anRF antenna 801 and a digital signal processor 802.

The RF antenna 801 may be a loop structure. The digital signal processor802 may include an analog-to-digital sampling circuit. Theanalog-to-digital sampling circuit may be configured to directly convertan analog signal (e.g., an RF signals received by the RF antenna 801) toa digital signal. In some embodiments, the digital signal processor 802may process the sampled digital signal, the processing includingprocedures of signal amplification, frequency conversion, filtering,notch. Based on magnetic resonance RF coil 800, analog components may beomitted, and more space of the RF coil 800 may be saved, allowing thedesigning of the RF coil 800 to be more diversified.

FIG. 9 is a schematic diagram illustrating an exemplary magneticresonance RF coil according to some embodiments of the presentdisclosure. As shown, the magnetic resonance RF coil 900 may include anRF antenna 901, an analog signal processor 902 and an analog-to-digitalconverter 903. The RF antenna 901 may be in a birdcage structure. Theanalog signal processor 902 and the analog-to-digital converter 903 maybe similar to the analog signal processor 403 and the analog-to-digitalconverter 404, respectively, and are not repeated herein.

FIG. 10 is a schematic diagram illustrating an exemplary magneticresonance RF coil 1000 according to some embodiments of the presentdisclosure. As shown, the magnetic resonance RF coil 1000 may include amagnetic resonance RF coil 1001 and a signal processor 1002.

The magnetic resonance RF coil 1001 may be configured to receive RFsignals. The RF signals may be emitted by the imaging object 150. Insome embodiments, the magnetic resonance RF coil 1001 may be an RFvolume coil. The RF volume coil may be in a structure of a birdcage. TheRF volume coil may be placed inside the gantry 145 of the MRI scannerand encompass the entire body of the imaging object 150. In someembodiments, the magnetic resonance RF coil 1001 may be a local coil.The local coil may be configured to encompass a portion of the body ofthe imaging object 150, for example, a head, a wrist, a shoulder, aspine, a foot, or the like, or a combination thereof. The magneticresonance RF coil 1001 may be made of one or more deformable materials.For example, the magnetic resonance RF coil 1001 may be made ofshape-memory alloy. The shape-memory alloy may recover to its originalshape under a recovering condition (e.g., a high temperature, a largestrain). The shape-memory alloy may include silver, cadmium, gold,nickel, titanium, hafnium, copper, zinc, or the like, or any combinationthereof. For another example, the magnetic resonance RF coil 1001 may bemade of deformable conductive materials. The deformable conductivematerials may include metallic materials such as solid metals, alloys,liquid metals, etc. The liquid metals may include mercury, aluminum,cesium, gallium, rubidium, or the like, or any combination thereof. Insome embodiments, the magnetic resonance RF coil 1001 may be asingle-channel coil, for example, a coil with one loop. In someembodiments, the magnetic resonance RF coil 1001 may be a coil arraywith a plurality channels. The number of channels may be 8, 16, 32, 64,etc.

The signal processor 1002 may be configured to process the RF signalsreceived by the magnetic resonance RF coil 901. The processing mayinclude procedures of analog signal amplification, filtering, notch,frequency conversion, analog-to-digital conversion, or the like, or acombination thereof.

The signal processor 1002 may include a matching circuit 1003, anamplifier 1004 and an analog-to-digital converter 1005. The matchingcircuit 1003 may be coupled to the magnetic resonance RF coil 1001 andthe amplifier 1004. The matching circuit 1003 may be configured to matchimpedance of the magnetic resonance RF coil 1001 and impedance of theamplifier 1004. The amplifier 1004 may be configured to amplify thesignal received by the magnetic resonance RF coil 1001. Theanalog-to-digital converter 1005 may be similar to the analog-to-digitalconverter 404, and is not repeated herein.

FIG. 11 is a schematic diagram illustrating an exemplary amplifyingcircuit according to some embodiments of the present disclosure. Asshown, the amplifying circuit 1100 may include an amplifier 1101, afirst adjusting circuit 1102, a second adjusting circuit 1103, a biascircuit 1104, and a third adjusting circuit 1105. The amplifying circuit1100 (or the amplifier 1101) may correspond to the amplifier describedelsewhere in the present disclosure (e.g., low noise amplifier 501, lownoise amplifier 601, low noise amplifier 701, amplifier 1004).

The amplifier 1101 may be configured to amplify an RF signal. Theamplifier 1101 may include a first port A, a second port B, a third portC, and a fourth port D. The first port A may be an input port of theamplifier 1101. The third port C may be an output port of the amplifier1101. The second port B and the fourth port D may be bypass ports of theamplifier 1101. The bypass ports may be configured to distribute poweror bias a circuit.

The first adjusting circuit 1102 may be configured to receive an RFsignal (e.g., an RF signal received by an RF coil). The first adjustingcircuit 1102 may be electrically coupled to an input port of theamplifying circuit 1100 (e.g., the first port A). The first adjustingcircuit 1102 may be configured to adjust a value of an input impedanceof the amplifier 1101. For example, the first adjusting circuit 1102 maybe configured to adjust the value of the input impedance of theamplifier 1101 to a real value (e.g., remove the imaginary part of theimpedance of the amplifier 1101). The first adjusting circuit 1102 mayinclude adjustable components. For example, the first adjusting circuit1102 may include a first resistor R1, a first capacitor C1, and a secondcapacitor C2. The first capacitor C1 and the second capacitor C2 may bevariable capacitors. The capacitance of a variable capacitor may bemechanically controlled or electronically controlled. A mechanicallycontrolled capacitor may include a vacuum variable capacitor, abutterfly capacitor, a split stator variable capacitor, a differentialvariable capacitor, or the like, or a combination thereof. Anelectrically controlled capacitor may include a voltage tuned variablecapacitor, an integrated circuit (IC) variable capacitor, or the like,or a combination thereof.

Similar to the first adjusting circuit 1102, the second adjustingcircuit 1103 may also be electrically connected to an input port A ofthe amplifier 1101. The second adjusting circuit 1103 may includeadjustable components. For example, the second adjusting circuit 1103may include a second resistor R2 and a third capacitor C3 and the thirdcapacitor C3 may be a variable capacitor. The second adjusting circuit1103 may also be configured to adjust the value of the input impedanceof the amplifier 1101 to a real value

The bias circuit 1104 may be configured to distribute power. The biascircuit 1104 may be electrically connected to a bypass port of theamplifier 1101 (e.g., the fourth port D). The bias circuit 1104 mayinclude a third resistor R3 and a fifth capacitor R5.

The third adjusting circuit 1105 may be configured to receive anamplified RF signal from the amplifier 1101. The third adjusting circuit1105 may be electrically connected to a bypass port of the amplifier1101 (e.g., the fourth port D). The third adjusting circuit 1105 may beconfigured to adjust a value of an output impedance of the amplifier1101. For example, the third adjusting circuit 1105 may be configured toadjust the value of the output impedance of the amplifier 1101 to a realvalue. The third adjusting circuit 1105 may include adjustablecomponents. For example, the third adjusting circuit 1105 may include afourth resistor R4, a fifth resistor R5 and a sixth capacitor C6. Thesixth capacitor C6 may be a variable capacitor.

In some embodiments, the input impedance of the amplifier 1101 may bedetermined based on the first adjusting circuit 1102 and the secondadjusting circuit 1103. The input impedance of the amplifier 1101 may bedetermined by the impedance of the first adjusting circuit 1102 and thesecond adjusting circuit 1103 according to a double terminal networkdescribed in FIG. 12. The value of the input impedance of the amplifier1101 may be expressed in the form of a first complex number. Themagnitude of the imaginary part of the first complex number may be setto 0 by adjusting capacitances of the first capacitor C1, the secondcapacitor C2, and/or the third capacitor C3.

In some embodiments, the output impedance of the amplifier 1101 may bedetermined based on the third adjusting circuit 1105. The outputimpedance of the amplifier 1101 may be determined by impedance of thethird adjusting circuit 1105 according to the double terminal networkdescribed in FIG. 12. The value of the output impedance of the amplifier1101 may be expressed in the form of a second complex number. Themagnitude of the imaginary part of the second complex number may be setto 0 by adjusting the capacitance of the sixth capacitor C6.

This description is intended to be illustrative, and not to limit thescope of the present disclosure. Many alternatives, modifications, andvariations will be apparent to those skilled in the art. The features,structures, methods, and other characteristics of the exemplaryembodiments described herein may be combined in various ways to obtainadditional and/or alternative exemplary embodiments. For example, theadjustable component configured to adjust the input impedance and theoutput impedance of the amplifier 1101 may also be a variable inductor,or a combination of a variable capacitor and a variable inductor. Asanother example, the pulse controller 111, the processing engine 122,and/or the display 123 may be integrated into an MRI console (notshown). Users may set parameters in MRI scanning, control the imagingprocedure, and view the images produced through the MRI console.However, those variations and modifications do not depart the scope ofthe present disclosure.

FIG. 12 is a schematic diagram illustrating an exemplary double terminalnetwork according to some embodiments of the present disclosure. Asshown in FIG. 12, the double terminal network 1200 may include an input1201 and an output 1202.

Merely by way of example, the input 1201 and the output 1202 may beexpressed as:

$\begin{matrix}{\begin{bmatrix}V_{1} \\V_{2}\end{bmatrix} = {\begin{bmatrix}z_{11} & z_{12} \\z_{21} & z_{22}\end{bmatrix}\begin{bmatrix}I_{1} \\I_{2}\end{bmatrix}}} & (1)\end{matrix}$

where V₁ may denote the voltage of the input 1201, V₂ may denote thevoltage of the output 1202, I₁ may denote the current of the input 1201,I₂ may denote the current of the output 1202, and z₁₁, z₁₂, z₂₁ and z₂₂may denote impedances between the input 1201 and the output 1202.

Merely by way of example, the impedances between the input 1201 and theoutput 1202 may be determined by:

$\begin{matrix}{z_{11}\overset{def}{=}\left. \frac{V\; 1}{I_{1}} \right|_{I_{2} = 0}} & (2) \\{z_{12}\overset{def}{=}\left. \frac{V\; 1}{I_{2}} \right|_{I_{1} = 0}} & (3) \\{z_{21}\overset{def}{=}\left. \frac{V\; 2}{I_{1}} \right|_{I_{2} = 0}} & (4) \\{z_{22}\overset{def}{=}\left. \frac{V\; 2}{I_{2}} \right|_{I_{1} = 0}} & (5)\end{matrix}$

By measuring the voltage and current of the amplifier, the inputimpedance and the output impedance of the amplifier may be calculated ascomplex values according to the formulae (2) to (5). The variablecomponents (e.g., C1, C2, C3, C6, etc.) in the amplifying circuit 1100may then be adjusted to remove the imaginary part of the compleximpedances.

This description is intended to be illustrative, and not to limit thescope of the present disclosure. Many alternatives, modifications, andvariations will be apparent to those skilled in the art. The features,structures, methods, and other characteristics of the exemplaryembodiments described herein may be combined in various ways to obtainadditional and/or alternative exemplary embodiments. For example, threeor more groups of pixels may be connected to a same signal transmissionboard. However, those variations and modifications do not depart thescope of the present disclosure.

It should be noted that the above description of the embodiments areprovided for the purposes of comprehending the present disclosure, andnot intended to limit the scope of the present disclosure. For personshaving ordinary skills in the art, various variations and modificationsmay be conducted in the light of the present disclosure. However, thosevariations and the modifications do not depart from the scope of thepresent disclosure.

Having thus described the basic concepts, it may be rather apparent tothose skilled in the art after reading this detailed disclosure that theforegoing detailed disclosure is intended to be presented by way ofexample only and is not limiting. Various alterations, improvements, andmodifications may occur and are intended to those skilled in the art,though not expressly stated herein. These alterations, improvements, andmodifications are intended to be suggested by this disclosure, and arewithin the spirit and scope of the exemplary embodiments of thisdisclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures or characteristics may be combined assuitable in one or more embodiments of the present disclosure.

Further, it will be appreciated by one skilled in the art, aspects ofthe present disclosure may be illustrated and described herein in any ofa number of patentable classes or context including any new and usefulprocess, machine, manufacture, or composition of matter, or any new anduseful improvement thereof. Accordingly, aspects of the presentdisclosure may be implemented entirely hardware, entirely software(including firmware, resident software, micro-code, etc.) or combiningsoftware and hardware implementation that may all generally be referredto herein as a “block,” “module,” “engine,” “unit,” “component,” or“system.” Furthermore, aspects of the present disclosure may take theform of a computer program product embodied in one or more computerreadable media having computer readable program code embodied thereon.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a frame wave. Such a propagated signal may takeany of a variety of forms, including electro-magnetic, optical, or thelike, or any suitable combination thereof. A computer readable signalmedium may be any computer readable medium that is not a computerreadable storage medium and that may communicate, propagate, ortransport a program for use by or in connection with an instructionexecution system, apparatus, or device. Program code embodied on acomputer readable signal medium may be transmitted using any appropriatemedium, including wireless, wireline, optical fiber cable, RF, or thelike, or any suitable combination of the foregoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object-oriented programming languagesuch as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB. NET,Python or the like, conventional procedural programming languages, suchas the “C” programming language, Visual Basic, Fortran 2008, Perl, COBOL2002, PHP, ABAP, dynamic programming languages such as Python, Ruby andGroovy, or other programming languages. The program code may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider) or in a cloud computing environment or offered as aservice such as a Software as a Service (SaaS).

Furthermore, the recited order of processing elements or sequences, orthe use of numbers, letters, or other designations therefore, is notintended to limit the claimed processes and methods to any order exceptas may be specified in the claims. Although the above disclosurediscusses through various examples what is currently considered to be avariety of useful embodiments of the disclosure, it is to be understoodthat such detail is solely for that purpose, and that the appendedclaims are not limited to the disclosed embodiments, but, on thecontrary, are intended to cover modifications and equivalentarrangements that are within the spirit and scope of the disclosedembodiments. For example, although the implementation of variouscomponents described above may be embodied in a hardware device, it mayalso be implemented as a software only solution—e.g., an installation onan existing server or mobile device.

Similarly, it should be appreciated that in the foregoing description ofembodiments of the present disclosure, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure aiding in theunderstanding of one or more of the various inventive embodiments. Thismethod of disclosure, however, is not to be interpreted as reflecting anintention that the claimed object matter requires more features than areexpressly recited in each claim. Rather, inventive embodiments lie inless than all features of a single foregoing disclosed embodiment.

In some embodiments, the numbers expressing quantities of ingredients,properties, and so forth, used to describe and claim certain embodimentsof the application are to be understood as being modified in someinstances by the term “about,” “approximate,” or “substantially.” Forexample, “about,” “approximate,” or “substantially” may indicate ±20%variation of the value it describes, unless otherwise stated.Accordingly, in some embodiments, the numerical parameters set forth inthe written description and attached claims are approximations that mayvary depending upon the desired properties sought to be obtained by aparticular embodiment. In some embodiments, the numerical parametersshould be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques. Notwithstandingthat the numerical ranges and parameters setting forth the broad scopeof some embodiments of the application are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspracticable.

Each of the patents, patent applications, publications of patentapplications, and other material, such as articles, books,specifications, publications, documents, things, and/or the like,referenced herein is hereby incorporated herein by this reference in itsentirety for all purposes, excepting any prosecution file historyassociated with same, any of same that is inconsistent with or inconflict with the present document, or any of same that may have alimiting affect as to the broadest scope of the claims now or laterassociated with the present document. By way of example, should there beany inconsistency or conflict between the description, definition,and/or the use of a term associated with any of the incorporatedmaterial and that associated with the present document, the description,definition, and/or the use of the term in the present document shallprevail.

It is to be understood that the embodiments of the application disclosedherein are illustrative of the principles of the embodiments of theapplication. Other modifications that may be employed may be within thescope of the application. Thus, by way of example, but not oflimitation, alternative configurations of the embodiments of theapplication may be utilized in accordance with the teachings herein.Accordingly, embodiments of the present application are not limited tothat precisely as shown and described.

In closing, it is to be understood that the embodiments of theapplication disclosed herein are illustrative of the principles of theembodiments of the application. Other modifications that may be employedmay be within the scope of the application. Thus, by way of example, butnot of limitation, alternative configurations of the embodiments of theapplication may be utilized in accordance with the teachings herein.Accordingly, embodiments of the present application are not limited tothat precisely as shown and describe.

What is claimed is:
 1. A magnetic resonance coil, comprising: an antennaconfigured to receive a radio frequency (RF) signal emitted from anobject, wherein the antenna does not resonate with the RF signal; asignal processor coupled to the antenna configured to process the RFsignal to generate a processed signal, wherein the signal processorcomprises: an amplifier coupled to the antenna configured to amplify theRF signal; and an adjusting circuit coupled to the amplifier configuredto adjust the magnitude of the imaginary part of an impedance of theamplifier.
 2. The magnetic resonance coil of claim 1, wherein theantenna is a non-resonant antenna.
 3. The magnetic resonance coil ofclaim 1, wherein the antenna is made of one or more deformableconductive materials.
 4. The magnetic resonance coil of claim 1, whereinthe antenna is a birdcage structure configured to receive the RF signalfrom an entire body of the object.
 5. The magnetic resonance coil ofclaim 1, wherein the antenna is a loop structure configured to receivethe RF signal from a portion of the object.
 6. The magnetic resonancecoil of claim 1, wherein the amplifier has an input port and an outputport, and the adjusting circuit includes at least one of an inputadjusting circuit or an output adjusting circuit, wherein the inputadjusting circuit is coupled to the input port of the amplifier andconfigured to adjust the magnitude of the imaginary part of an inputimpedance of the amplifier, and the output adjusting circuit is coupledto the output port of the amplifier and configured to adjust themagnitude of the imaginary part of an output impedance of the amplifier.7. The magnetic resonance coil of claim 6, wherein the input adjustingcircuit includes a first adjustable component, the magnitude of theimaginary part of the input impedance of the amplifier is adjusted byadjusting at least one of the capacitance or the inductance of the firstadjustable component, and the output adjusting circuit includes a secondadjustable component, the magnitude of the imaginary part of the outputimpedance of the amplifier is adjusted by adjusting at least one of thecapacitance or the inductance of the second adjustable component.
 8. Themagnetic resonance coil of claim 1, wherein the amplifier is adifferential amplifier.
 9. The magnetic resonance coil of claim 1,further comprising: a matching circuit coupled between the antenna andthe amplifier and configured to match an impedance of the antenna and animpedance of the amplifier.
 10. The magnetic resonance coil of claim 9,wherein the matching circuit is a broadband matching circuit thatmatches the impedance of the antenna and the impedance of the amplifierover a frequency range of the broadband signals.
 11. The magneticresonance coil of claim 1, wherein the adjusting circuit includes atleast one of a variable capacitor or a variable conductor.
 12. Themagnetic resonance coil of claim 1, wherein the signal processor furthercomprises a filter coupled to the amplifier.
 13. The magnetic resonancecoil of claim 1, wherein the signal processor further comprises aheterodyne receiver or a homodyne receiver coupled to the amplifier. 14.The magnetic resonance coil of claim 1, wherein the signal processor isa direct sampling structure, the signal processor comprising: ananalog-to-digital converter configured to convert the RF signal to adigital signal.
 15. The magnetic resonance coil of claim 1, wherein theantenna is configured without capacitive elements on conductivematerials.
 16. The magnetic resonance coil of claim 1, wherein theantenna is configured with no impedance matching circuit.
 17. Themagnetic resonance coil of claim 1, wherein the amplifier is configuredwith an input impedance greater than 500 Ohms.
 18. The magneticresonance coil of claim 1, wherein the antenna is configured with nocoupling unit, nor decoupling unit.
 19. The magnetic resonance coil ofclaim 1, wherein the magnetic resonance coil is implemented in amulti-nuclear magnetic resonance system relating to a plurality ofatomic nuclei, the plurality of atomic nuclei comprising: phosphorusatom or sodium atom.
 20. A magnetic resonance imaging (MRI) system,comprising: a main electromagnet configured to generate a uniformmagnetic field on an object; a gradient electromagnet configured togenerate a gradient magnetic field on the object; a transmitting coilconfigured to transmit a first radio frequency (RF) signal to theobject; a receiving coil configured to receive and process a second RFsignal emitted from the object in response to the first RF signal, thereceiving coil including: an antenna configured to receive a radiofrequency (RF) signal emitted from an object, wherein the antenna doesnot resonate with the RF signal; and a signal processor coupled to theantenna configured to process the RF signal to generate a processedsignal; a processor configured to generate an image of the object basedon the processed signal; and a display configured to display thegenerated image of the object, wherein the signal processor comprises:an amplifier coupled to the antenna configured to amplify the RF signal,and an adjusting circuit coupled to the amplifier configured to adjustthe magnitude of the imaginary part of an impedance of the amplifier.